Vacuum relay



Jan- 5, 1960 l.. B. sTEwARD Erm 2,920,162

VACUUM RELAY Filed Jan. 3. 1956 /N VEN TOR 3 LEW/S B; STEWAR JAC/f S. HAWK/NS @Mx/M their ATTORNEY United States Patent VACUUM RELAY Lewis B. Steward, San Jose, and Jack S. Hawkins, Campbell, Calif., assignors to `Iennngs Radio Manufacturing Corporation, San Jose, Calif., a corporation of California Application January 3, 1956, Serial No. 556,942

9 Claims. (Cl. 200-104) Our invention relates to a vacuum relay or switch of special usefulness as a transmitting and receiving switch in the communication eld.

One of the objects of our invention is the provision of a switch of the type described of low Contact resistance, and free of tendency to arc over.

Another object of our invention is the provision of a small size, low operating power, 4-pole double throw switch capable of safely handling comparatively high voltages.

Another object of our invention is the provision of a multi-polar vacuum relay in which the contact resistance remains substantially constant for the life of the implement.

Still another object is the provision of a multi-pole double throw switch with very few moving parts, but all of these arranged in a vacuumized chamber to be operated by electromagnetic means outside the chamber and in which the energizing coil is readily replaceable with one of like or different characteristics.

Another object is the provision of a switch of particular usefulness in radio frequency work because of very low inductance in its contact parts.

Still another important object of our invention is the provision of a vacuum switch in which the electrical demands in aviation use are fully met, as well as those imposed by mechanical shock and vibration. This switch may be immersed in an insulating liquid if the need arises, since the external resistance path is lower than the internal resistance.

A very important object of our invention is the provision of a switch which can be operated with no dependence whatever upon `surrounding atmospheric pressure; and which can therefore be used with uniform operating certainty and efficiency at any altitude either in fixed or aircraft installations.

` Other objects will be brought out in the following description of the invention. We do not limit ourselves to the showing made by said description and the drawings, since we may use variant forms of the invention within the scope of the appended claims.

Referring to the drawings:

Fig. l is a vertical sectional view taken in the long axis of the switch.

`Fig. -2 is an end elevation of our relay, the end wall being partly broken away to disclose the underlying parts.

Fig. 3 is a detail on an enlarged scale, of part of the armature assembly.

Fig. 4 is a detail on an enlarged scale of the contact points on their rocker. The view is taken in the direction indicated by the arrow 4 in Fig. 2.

In terms of broad inclusion our switch comprises a glass bulb closed on one end with a metallic wall to form a vacuumized envelope. The wall is formed in part by a ferrous cylindrical housing concentric with the long axis of the bulb and on which the bulb vis secured by a copper seal ring, and in part by a copper transverse wall across the adjacent end of the housing. The copper wall ice is brazed to the housing and forms the bottom of a coil chamber therein, lying on the side opposite to the vacuum chamber. A ferrous cylindrical core concentric with the housing is integrally united with the copper wall, extending on one side into the vacuumized chamber and on the other side into the coil chamber.

Coil means for energizing the core is disposed in the coil chamber of the housing, preferably being mounted on the core itself. A cover plate closing the coil chamber and housing is secured by a single screw into the end of the core so that the coil may be quickly removed and replaced.

Within the vacuumized chamber Iare a plurality of groups of three contact rods, each group comprising a central rod between two side rods. The rods are spaced apart and xedly mounted in the glass bulb. Each rod extends through and is hermetically sealed in the glass bulb and terminates in a lead external to the vacuumized chamber.

A disk or plate armature slidably mounted within the vacuumized chamber is responsive to a compression spring in one direction, and to the energized coil in the opposite direction; and carries a dielectric disk on which are mounted a plurality of spring arms, one extending toward each adjacent group of contact rods. Each spring arm engages a spring pressed rocker journaled on the central contact rod, which also constitutes a bracket supporting the rocker on the glass bulb. A pair of spaced Contact points is carried by the rocker; and the parts are so arranged that with movement of the armature in one direction, each of the rockers is moved against the resistance of its spring so that one of the contact points of each pair firmly engages a side contact rod to complete a circuit through the central or bracket contact rod and one side contact rod of that particular group of three rods; and with movement of the armature in the opposite direction each rocker is tipped so that the other contact point of each pair engages the other side contact rod of the same group of rods, opening the first circuit and closing a second through the central bracket contact rod and the other side contact rod.

The armature and dielectric disk are slidably and rotatably arranged on the tungsten stem rigidly fixed in the inner end of the core, and extending concentrically therewith and with the long central axis of the implement into the vacuumized chamber past the plane through the contact rods.

The energizing means for the core is a coil arranged to t closely over the core and entirely within the housing. When the cover plate is fastened in place by a single screw the magnetic path around the coil is closed so that magnetic eiciency is assured. Since the movable contact points are insulated from their actuating assembly, the latter and its connected housing is never part of the controlled circuit which includes only the xed contact rods and the movable contact points. In this construction no pigtails are necessary internally, no electrical loops are set up, and clean contacts are assured.

In greater detail, our vacuum relay comprises a vacuumized chamber 1, within a glass or other dielectric bulb 2, closed at its base end with the copper wall 3, brazed into the cylindrical ferrous housing shell 4. The shell is joined to the glass bulb in hermetically tight unions by the intervening copper seal 5, brazed to the shell and united to the bulb edge in a well known metal-to-glass seal.

A magnetic core 6 of ferrous metal is brazed to the wall 3, extending on both sides of the wall and concentric with the shell in the long axis of the implement. A plate 7, secured to the core at its outer end, by a screw 8, provides a closure for the open end of the shell 4, within which is the coil 9 for energizing the core. Lead wires extending through insulating sleeves arranged in the cover plate provide means for connecting the coil into a control circuit through external lead screws 11 which extend through the side of the copper mounting flange 12 extending from the plate 7. It is noted that this arrangement facilitates the replacement of the coil assembly with the same or differing electrical values, without disturbing the relay otherwise.

Adjacent the inner end of the core and within the vacuum chamber is a ferrous armature disk 13 fixed on a cylindrical copper sleeve 1d, slidably journaled on the stem 15 extending rigidly and concentrically from the end of the core.

A spring 18 surrounding the inner end of the core and bearing against the wall 3 normally presses the armature and sleeve away from the core. The copper sleeve 14 is formed with a ange 21 against which a ceramic plate or disk 22 between two thin washers 2,3 is firmly secured by a nut 24, threaded on the end of the sleeve and fixed thereon by distortion of the threads against the nut.

Riveted rigidly by pins 27 around the perimeter of the ceramic disk at 90 intervals, are four identical lnconel bracket plates 23. Each plate is provided along its outer edge with a substantially perpendicular lug 29, having an aperture through which projects a spring arm 31. Each spring arm is a short length of cleaned and annealed tungsten wire having a diameter of about .040. It is spot welded to its associated bracket plate so that a free end extends radially from the ceramic disk in the nature of a resilient cantilever arm.

In order to provide a multiplicity of external leads 32 for connection to electrical circuits to be controlled, a plurality of identical groups of contact rods are provided. In the present embodiment there are four such groups, each with a center rod between two side rods. Each rod is separately sealed in the glass bulb so that it projects radially outward therefrom in the external lead 32. Inside the bulb, each central contact rod extends radially inwardly in a bracket or journal portion 33; and each of the side contact rods is bent inwardly to provide a portion 34, perpendicular to the journal portion 33 of the central contact rod and lying in the same plane. As shown in Figs. 2 and 4, the inner ends of the side contact rods are spaced a short distance from the central rod, which in most installations will be hot Means associated with each group of rods are provided to bridge selectively the rod 33 and one or the other of the side contact rods 34. Pivotally journaled on the portion 33 of each central contact rod is a generally U-shaped rocker bracket 36. The rocker bracket is preferably spring tempered Inconel, with the arms 37 apertured to lit around the central rod portion 33. Cradled between the arms 37 adjacent the base of the U is an Inconel contact bridge plate 39. The ends of the bridge plate project beyond the base of the rocker bracket, each bridge plate serving to support a pair of spaced parallel cylindrical tungsten contact points 41, which are integrally secured thereto as by brazing.

The pair of spaced contact points, one at each end of the bridge plate, are thus in position to be rocked to close selectively the gap between the central rod portion 33 and the end of the associated side rod. The extreme end of each side contact red is cylindrically shaped to meet with the contact point in line engagement. A laterally projecting apertured lug 42 on the rocker bracket, engaged by the free end of spring arm 31, serves as a lever to rock the rocker bracket clockwise when the coil is energized, pulling the armature and its connected ceramic disk downwardly. Movement of each rocker and contact point assembly in this direction simultaneously closes the circuit between the central rod and the right hand side rod, Fig. 2, and opens the circuit between the central rod and the other (left) side rod. Deenergizing the coil results in coil spring Il@ pressing the armature and ceramic disk outwardly to the left in Fig. l, thus permitting the 4. contact points 4l to rock in the opposite (counterclockwise) direction. Each lead 32 to the left of each central rod in each group is thus placed in circuit with the central rod. This relationship of the parts is preferably maintained as the normal condition of the relay.

To secure maximum usefulness and adaptability of the relay in a variety of installations, such as aircraft, surface vessels, and artillery, the relay is designed to operate in whatever position it may be placed. In the position shown, each left Contact point closes the circuit between the left side rod and the central rod. The contact point is resiliently held in this position by a coil compression spring 43 wound around and anchored at one end to the central rod 33 and at the other end anchored under the lug 42, thus normally urging the rocker bracket in a counterclockwise direction. The pressure exerted by this spring 43 is in addition to an increment of resilient pressure applied by the outward thrust of main coil spring 18 and spring arm 3l. Because of the difficulty in gauging the free length of coil spring 18, this spring is gauged to support the weight of the armature-ceramic disk assembly, and in addition add an increment of outward thrust. This insures that spring 43 will not be hampered in any way from closing the circuit, regardless of the position of the switch in space. These forces, resiliently applied, insures that the relay will operate as intended regardless of position or vibration. A stop disk 44 spot welded on the end of each central rod acts as a safety stop for the rocker bracket assembly, and cooperating with spring 43, insures that the contact points will always remain in operative position on the central rod.

When the coil 9 is energized, the armature is pulled down, tensioning spring 18 and displacing spring arm 31 downwardly against the tension of spring 43. Downward displacement of the spring arm 31 pivots the rocker bracket clockwise, bringing the right hand contact point into engagement with the end of the right hand side contact rod. This position of the parts is maintained until the coil 9 is deenergized. The parts are preferably proportioned so that the contact point engages the right side contact rod before the armature comes to rest against the inner end of the housing shell 4, so that the contacts are held in resilient engagement even during vibration of the whole implement.

As shown in Fig. 4, constant electrical contact is maintained between the central rod 33 and contact points 41. rIhis insures that the contacts 41 will always be in full engagement with the contact rod about which they oscillate. Since movement of the parts is slight, wear is at a negligible level and dependable switching is insured for an extremely long useful life. Our relay measuring about 4% in diameter by 4l/2 long and as illustrated and described herein is conservatively rated for lO amperes RF. current and a static voltage rating of 10,000 volts per contact. These are safe operating values. In our experi- :tents we have operated our relays with 30 amperes and they will withstand static voltages to 20,000 volts.

We claim:

l. A switch comprising a vacuumized envelope, a plurality of spaced contact rods extending through the wall of the envelope and constituting terminal leads on the outside of the envelope and fixed contact rods on the inside thereof, a movable `contact point arranged on one of the fixed contact rods to engage and disengage selectively another of the fixed contact rods, a fixed stem inside the envelope, and means on the lixed stem to move the movable contact point to engage the selected contact rod.

2. A switch comprising a vacuumized envelope, a plurality of spaced contact rods extending through the wall of the envelope and constituting.,r terminal leads on the outside of the envelope and tixed contact rods on the inside thereof, a movable contact point arranged on one of the xed contact rods to engage and disengage selectively another of the xed contact rods, said contact point being a cylinder and the contact rods presenting adjacent cylindrical surfaces meeting the contact point in line engagement, a fixed stern inside the envelope, and means on the fixed stern to move the movable contact point to engage the selected contact rod.

3. A switch comprising a vacuumized envelope, a plurality of spaced contact rods extending through the wall of the envelope and constituting terminal leads on the outside of the envelope and fixed contact rods on the inside thereof, a movable contact point arranged on one of the fixed contact rods to engage and disengage selectively another of the fixed contact rods, a fixed stern inside the envelope, and means on the fixed stem to move the movable cont-act point to engage the selected contact rod, said means for moving the contact point in one direction comprising a compression spring within the vacuumized chamber and for moving the contact point in the opposite direction comprising an armature within the chamber and a magnetic coil outside the chamber.

4. A switch comprising a vacuumized envelope, a group of three spaced contact rods extending through the wall of the envelope and constituting terminal leads on the outside of the envelope and fixed contact rods on the inside thereof, a fixed stem inside the envelope, a dielectric plate slidably arranged on the stern, a pair of spaced contact points movably mounted on one of the fixed contact rods to resiliently engage and disengage selectively the two remaining fixed contact rods, means resiliently connecting the dielectric plate and said pair of spaced contact points, and mechanical means inside the envelope and electromagnetic means outside the en velope cooperating with said dielectric plate to effect engaging and disengaging movement of the contact points.

5. A switch in accordance with claim 4 in which spring means are associated with said pair of contact points to normally rock one contact point of the pair into resilient engagement with two of the fixed contact rods.

6. A switch in :accordance with claim 4 in which the spaced contact points are movably mounted on the central contact rod of the group to engage and disengage selectively the side contact rods.

7. A switch in accordance with claim 6 in which spring means are associated with the pair of contact points to normally rock one contact point of the pair into resilient engagement with one of the side contact rods and rock the other contact points to disengage the other side contact rod.

8. A switch comprising a vacuumized envelope having a metallic end wall, a magnetically energizable core integral with the end wall and extending on both sides thereof, a stem within the envelope and xed on the core, a sleeve slidable on the stem, a magnetically responsive armature disk fixed on the sleeve for movement therewith, a compression spring interposed between the wall and armature disk and urging the armature away from the core, a dielectric disk fixed on the sleeve for movement therewith, a plurality of spaced contact rods extending through the wall of the envelope and constituting terminal leads on the outside of the envelope and fixed contact rods on the inside thereof, a contact point mounted on one of the fixed contact rods in position to engage the other fixed contact rods when the armature moves away from the core in response to the spring, and a magnetic coil around the outer end of the core for energizing the core to pull the armature toward the core and disengage the contact point from said other fixed contact rods.

9. A switch comprising a vacuumized envelope having a metallic end wall, a magnetically energizable core integral with the end wall and extending on both sides thereof, a stem within the envelope and fixed on the core, a sleeve slidable on the stem, a magnetically responsive armature disk fixed on the sleeve for movement therewith, a compression spring interposed between the wall and armature disk and urging the armature away from the core, a dielectric disk fixed on the sleeve for movement therewith, at least three spaced contact rods extending through the envelope wall to provide fixed central and two side contact rods on the inside thereof, and first and second contact points mounted on the fixed central rod in such position that when the armature responds to the spring the first contact point engages the central contact rod and one of the side rods, and when the armature responds to the magnetically energized core the first contact point disengages the rods and the second contact point engages the central contact rod and the other side contact rod.

References Cited in the file of this patent UNITED STATES PATENTS 665,541 Moskowitz `lan 8, 1901 761,694 Murphy June 7, 1904 890,840 Butler et al. June 16, 1908 1,285,786 Nies Nov. 26, 1918 1,726,392 Goff Aug. 27, 1929 1,941,273 Prince Dec. 26, 1933 2,180,661 Baruch Nov. 21, 1939 2,383,973 Jones Sept. 4, 1945 2,476,794 Austin July 19, 1949 2,485,532 Johnson Oct. 18, 1949 2,539,547 Mossman et al Jan. 30, 1951 2,775,671 Dreyfus Dec. 25, 1956 FOREIGN PATENTS 263,990 Great Britain Jan. 13, 1927 451,596 Germany Oct. 28, 1927 

